High waves warning issued for North Sumatra waters from 19-22 May 2026

The Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG) has stated that high waves are likely to occur in several waters across North Sumatra from 19 to 22 May 2026, necessitating caution as they may disrupt maritime navigation.

Dasmian Sulviani, a forecaster at the BMKG Class II Maritime Meteorological Station in Belawan, Medan, reported on Monday that wave heights could reach between 1.25 and 2.5 metres. These conditions are expected in the western waters of the Batu Islands, the western waters of the Nias Islands, and the Indian Ocean west of the Nias Islands.

These high wave conditions pose a risk to fishermen using small boats if wind speeds reach 15 knots and wave heights reach 1.25 metres, as well as to barges if wind speeds reach 16 knots and wave heights reach 1.5 metres.

Meanwhile, Endah Paramitha, a forecaster from the BMKG Region I Medan, noted that weather in North Sumatra on Tuesday (19/5) still carries the potential for light to moderate rainfall.

Specifically, the weather in North Sumatra on Tuesday morning is expected to be partly cloudy with the potential for light rain in South Nias and North Nias. During the afternoon, light to moderate rain is possible in the Langkat, Samosir, and Simalungun regions.

By nightfall, light to moderate rain is anticipated in Langkat and Asahan, while the early hours of the morning may bring cloudy skies and light rain in Langkat, Deli Serdang, and Serdang Bedagai.

‘Be alert to the potential for moderate intensity rain, which may be accompanied by lightning and strong winds in the mountainous areas, eastern slopes, and the eastern and western coasts of North Sumatra,’ she added.